In 1983, the sight of someone talking a mile a minute in an otherwise empty automobile would be a little unsettling, the San Diego Padres played baseball in Jack Murphy Stadium, and, if you needed to call home to be reminded of what it was you were supposed to pick up at the grocery store, you had to find a telephone booth. But today, the proliferation of cellular technology has changed this, and many more characteristics of our lives. Today, everyone talks a mile a minute in an otherwise empty car and the grocery store is full of confused men, wandering aimlessly through the isles and being directed through instructions received through a cellular telephone. And the San Diego Padres, well they play in a stadium named after one of the pioneers in cellular technology. The present invention herein disclosed is yet another innovative idea to enhance the growth, reliability and applicability of this technology.
Fourth generation wireless networks will likely be based on packet transport technology. A likely candidate is IP, although other alternatives are possible. These systems will use general networking techniques, allowing them to be fully integrated with wireline networks. Networks based on code-division multiple-access (“CDMA”) technology and wideband CDMA (“W-CDMA”), including both second and third generation systems, face special challenges when using packet technology because of the network architectures built to handle the air interface specific processing functions. Thus, there is a need in the art for a method to enable CDMA systems to use general networking techniques, and hence be part of fourth generation wireless networks.
When a mobile device transmits an IP packet, it is fragmented into small frames for transmission over the air. These frames must be re-assembled into full IP packets before being transmitted into the IP backbone network. If this re-assembly function could take place at the base station, end-to-end IP networking could be used in wireless networks, making them fully compatible with wireline networks.
However, in current CDMA networks, this is difficult because the networks require a function called frame selection to be performed in order to support what is called soft-handoffs. During a soft handoff, frames transmitted from a mobile are received by more than one base station. These frames are forwarded to a common piece of equipment in the network called a frame selector. The frame selector picks the frame with the highest probability of being received without error, typically based on a measurement embedded in the frame, and discards the other frames. Only after this function is performed can the reassembly process take place. A dual function is performed in the reverse direction. Therefore, IP networking must end at the point in the network where frame selection takes place. Thus, there is a need in the art for a method to perform re-assembly of the fragmented IP packets at the base station of a CDMA network.
In current CDMA networks, and those planned for third generation systems, this function is performed inside the network at a central point called the Radio Network Controller. There are two reasons for this. First, base stations are connected to the backbone network over low-speed transmission lines. Therefore, it is difficult for them to exchange traffic with each other to perform this function. Second, the measurement information embedded in the frames is used in power control algorithms that are run on processors inside the networks. Thus, there is a need in the art for a frame selection function, and hence packet reassembly function, to be performed at the base station, hence allowing end-to-end IP networking.